A conventional clothes dryer comprises a drum, a heating coil, a blower, a filter, a drum motor to turn the drum, a blower motor to drive the blower, an air channel to direct air flow created by the blower, and a control system. In order to initiate a drying cycle, the user of the clothes dryer inserts wet fabrics inside of the drum and selects an appropriate heat level and drying time. The control system responds to these selections by energizing the drum motor and the blower motor. The drum motor turns the drum in order to tumble the wet fabrics as they are dried. The blower motor drives the blower so that air is drawn into the clothes dryer from ambient. The air channel directs the air as the air moves through the clothes dryer. Accordingly, the air is first passed over the heating coil where the air is heated. The heated air is directed into the drum where it evaporates water from the wet fabrics. Moisture laden air passes from the drum through the filter and then is exhausted from the clothes dryer to ambient.
The air supplied to the drum is heated by the heating coils because warm air picks up more moisture than cool air. The moist air is passed through the filter in order to filter out lint and other particles before the air is exhausted from the dryer. Typically, the exhausted air is vented outside of the building in which the clothes dryer is located.
This operation continues for the selected amount of drying time, after which the clothes dryer shuts off. However, some clothes dryers have humidity sensors to sense the humidity of the air exhausted from the clothes dryer. When the humidity sensor senses that the humidity of the exhaust air is below a pre-determined level (indicating, by inference, that the fabrics are dry), the control system of such a clothes dryer terminates its drying operation. Still other clothes dryers have conductive fingers to sense the amount of moisture in the fabrics being dried by the clothes dryer. When the conductivity across the conductive fingers decreases below a pre-determined level (indicating, by inference, that the fabrics are dry), the control system of such a clothes dryer terminates its drying operation.
The heating coil typically used in conventional clothes dryers is an electric resistant heater. Following energization, an electric resistance heater heats up slowly causing a delay in delivering heated air to the drum of a clothes dryer. The longer the delay, the longer the time required to dry fabrics. Furthermore, such heating coils dry primarily through convection heating. Convection heating has limited sanitation capabilities. In order to adequately sanitize the fabrics being dried, the electric resistance heater would have to be operated at a temperature which might damage those fabrics. Accordingly, to prevent such damage, an electric resistance heater of a clothes dryer is operated at a temperature which is sufficient to dry fabrics but which is insufficient to adequately sanitize them.
The present invention is intended to solve one or more of the above-noted problems.